平面内任一向量都可以构造成具有相同起点的两向量的差,这两向量的共同起点可以是任意的,如→AB既可以表示成→AB=→OB-→OA,也可以是表示成→AB=→MB-→MA.把一个向量构造成具有相同起点的两向量的差解题,关键 Any vector in the plane can be constructed as a difference between two vectors having the same starting point. The common starting point of the two vectors can be any, for example, → AB can be expressed as → AB = → OB → OA, → AB = → MB- → MA. To construct a vector as a two-vector difference problem with the same starting point, the key